The group plans to sign an agreement May 19 to drop the suit against Chisso Corp., Kyodo News agency said. Beginning in 1932 and peaking in the 1950s, Chisso dumped tons of mercury compounds into the sea around Minamata, about 660 miles southwest of Tokyo, creating Japan's worst case of industrial poisoning.

Of the five major victims' groups, four already have signed agreements with Chisso. The latest group signing on is the largest of the five. Under the plan, victims receive $209 a month from the government for medical expenses and a lump sum payment of $24,800 from Chisso.